Deforestation impacts on Amazon-Andes hydroclimatic connectivity

2021 ◽  
Author(s):  
Juan Sierra ◽  
Jhan Carlo Espinoza ◽  
Clementine Junquas ◽  
Jan Polcher ◽  
Miguel Saavedra ◽  
...  
Keyword(s):  
South America ◽  
Transition Region ◽  
Amazon Basin ◽  
Climate Models ◽  
Regional Climate ◽  
Austral Summer ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Deforestation Rates ◽  
Tropical South America

<p>The Amazon rainforest is a key component of the climate system and one of the main planetary evapotranspiration sources. Over the entire Amazon basin, strong land-atmosphere feedbacks cause almost one third of the regional rainfall to be transpired by the local rainforest. Maximum precipitation recycling ratio takes place on the southwestern edge of the Amazon basin (a.k.a. Amazon-Andes transition region), an area recognized as the rainiest and biologically richest of the whole watershed. Here, high precipitation rates lead to large values of runoff per unit area providing most of the sediment load to Amazon rivers. As a consequence, the transition region can potentially be very sensitive to Amazonian forest loss. In fact, recent acceleration in deforestation rates has been reported over tropical South America. These sustained land-cover changes can alter the regional water and energy balances, as well as the regional circulation and rainfall patterns. In this sense, the use of regional climate models can help to understand the possible impacts of deforestation on the Amazon-Andes zone.</p><p>This work aims to assess the projected Amazonian deforestation effects on the moisture transport and rainfall behavior over tropical South America and the Amazon-Andes transition region. We perform 10-year austral summer simulations with the Weather Research and Forecasting model (WRF) using 3 one-way nested domains. Our finest domain is located over the south-western part of the basin, comprising two instrumented Andean Valleys (Zongo and Coroico river Valleys). Convective permitting high horizontal resolution (1km) is used over this domain. The outcomes presented here enhance the understanding of biosphere-atmosphere coupling and its deforestation induced disturbances.</p>

scholarly journals Global Radiative Flux and Cloudiness Variability for the Period 1959–2010 in Belgium: A Comparison between Reanalyses and the Regional Climate Model MAR

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 262 ◽  
Author(s):  
Coraline Wyard ◽  
Sébastien Doutreloup ◽  
Alexandre Belleflamme ◽  
Martin Wild ◽  
Xavier Fettweis
Keyword(s):  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Radiative Flux ◽  
Added Value ◽  
Historical Trends ◽  
The Mean

The use of regional climate models (RCMs) can partly reduce the biases in global radiative flux (Eg↓) that are found in reanalysis products and global models, as they allow for a finer spatial resolution and a finer parametrisation of surface and atmospheric processes. In this study, we assess the ability of the MAR («Modèle Atmosphérique Régional») RCM to reproduce observed changes in Eg↓, and we investigate the added value of MAR with respect to reanalyses. Simulations were performed at a horizontal resolution of 5 km for the period 1959–2010 by forcing MAR with different reanalysis products: ERA40/ERA-interim, NCEP/NCAR-v1, ERA-20C, and 20CRV2C. Measurements of Eg↓ from the Global Energy Balance Archive (GEBA) and from the Royal Meteorological Institute of Belgium (RMIB), as well as cloud cover observations from Belgocontrol and RMIB, were used for the evaluation of the MAR model and the forcing reanalyses. Results show that MAR enables largely reducing the mean biases that are present in the reanalyses. The trend analysis shows that only MAR forced by ERA40/ERA-interim shows historical trends, which is probably because the ERA40/ERA-interim has a better horizontal resolution and assimilates more observations than the other reanalyses that are used in this study. The results suggest that the solar brightening observed since the 1980s in Belgium has mainly been due to decreasing cloud cover.

scholarly journals The impact of RCM formulation and resolution on simulated precipitation in Africa

2019 ◽  
Author(s):  
Minchao Wu ◽  
Grigory Nikulin ◽  
Erik Kjellström ◽  
Danijel Belušić ◽  
Colin Jones ◽  
...  
Keyword(s):  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Added Value ◽  
Primary Control ◽  
Model Formulation ◽  
Simulated Precipitation ◽  
Mean Climate ◽  
The Impact

Abstract. We investigate the impact of model formulation and horizontal resolution on the ability of Regional Climate Models (RCMs) to simulate precipitation in Africa. Two RCMs – SMHI-RCA4 and HCLIM38-ALADIN are utilized for downscaling the ERA-Interim reanalysis over Africa at four different resolutions: 25, 50, 100 and 200 km. Additionally to the two RCMs, two different configurations of the same RCA4 are used. Contrasting different RCMs, configurations and resolutions it is found that model formulation has the primary control over many aspects of the precipitation climatology in Africa. Patterns of spatial biases in seasonal mean precipitation are mostly defined by model formulation while the magnitude of the biases is controlled by resolution. In a similar way, the phase of the diurnal cycle is completely controlled by model formulation (convection scheme) while its amplitude is a function of resolution. Although higher resolution in many cases leads to smaller biases in the time mean climate, the impact of higher resolution is mixed. An improvement in one region/season (e.g. reduction of dry biases) often corresponds to a deterioration in another region/season (e.g. amplification of wet biases). The experiments confirm a pronounced and well known impact of higher resolution – a more realistic distribution of daily precipitation. Even if the time-mean climate is not always greatly sensitive to resolution, what the time-mean climate is made up of, higher order statistics, is sensitive. Therefore, the realism of the simulated precipitation increases as resolution increases. Our results show that improvements in the ability of RCMs to simulate precipitation in Africa compared to their driving reanalysis in many cases are simply related to model formulation and not necessarily to higher resolution. Such model formulation related improvements are strongly model dependent and in general cannot be considered as an added value of downscaling.

scholarly journals Regional Climate Modeling over South America: A Review

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Silvina A. Solman
Keyword(s):  
Climate Change ◽  
South America ◽  
Climate Models ◽  
Climate Modeling ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Regional Climate Models ◽  
Regional Climate Modeling ◽  
South American ◽  
Sensitivity Studies

This review summarizes the progress achieved on regional climate modeling activities over South America since the early efforts at the beginning of the 2000s until now. During the last 10 years, simulations with regional climate models (RCMs) have been performed for several purposes over the region. Early efforts were mainly focused on sensitivity studies to both physical mechanisms and technical aspects of RCMs. The last developments were focused mainly on providing high-resolution information on regional climate change. This paper describes the most outstanding contributions from the isolated efforts to the ongoing coordinated RCM activities in the framework of the CORDEX initiative, which represents a major endeavor to produce ensemble climate change projections at regional scales and allows exploring the associated range of uncertainties. The remaining challenges in modeling South American climate features are also discussed.

scholarly journals Evaluation of regional climate models ALARO-0 and REMO2015 at 0.22° resolution over the CORDEX Central Asia domain

2021 ◽  
Vol 14 (3) ◽  
pp. 1267-1293
Author(s):  
Sara Top ◽  
Lola Kotova ◽  
Lesley De Cruz ◽  
Svetlana Aniskevich ◽  
Leonid Bobylev ◽  
...  
Keyword(s):  
High Resolution ◽  
Central Asia ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Maximum Temperature ◽  
The Tibetan Plateau ◽  
Climate Information ◽  
Climate Data

Abstract. To allow for climate impact studies on human and natural systems, high-resolution climate information is needed. Over some parts of the world plenty of regional climate simulations have been carried out, while in other regions hardly any high-resolution climate information is available. The CORDEX Central Asia domain is one of these regions, and this article describes the evaluation for two regional climate models (RCMs), REMO and ALARO-0, that were run for the first time at a horizontal resolution of 0.22∘ (25 km) over this region. The output of the ERA-Interim-driven RCMs is compared with different observational datasets over the 1980–2017 period. REMO scores better for temperature, whereas the ALARO-0 model prevails for precipitation. Studying specific subregions provides deeper insight into the strengths and weaknesses of both RCMs over the CAS-CORDEX domain. For example, ALARO-0 has difficulties in simulating the temperature over the northern part of the domain, particularly when snow cover is present, while REMO poorly simulates the annual cycle of precipitation over the Tibetan Plateau. The evaluation of minimum and maximum temperature demonstrates that both models underestimate the daily temperature range. This study aims to evaluate whether REMO and ALARO-0 provide reliable climate information over the CAS-CORDEX domain for impact modeling and environmental assessment applications. Depending on the evaluated season and variable, it is demonstrated that the produced climate data can be used in several subregions, e.g., temperature and precipitation over western Central Asia in autumn. At the same time, a bias adjustment is required for regions where significant biases have been identified.

scholarly journals Future change of climate in South America in the late twenty-first century: intercomparison of scenarios from three regional climate models

2009 ◽  
Vol 35 (6) ◽  
pp. 1073-1097 ◽  
Author(s):  
Jose A. Marengo ◽  
Tercio Ambrizzi ◽  
Rosmeri P. da Rocha ◽  
Lincoln M. Alves ◽  
Santiago V. Cuadra ◽  
...  
Keyword(s):  
South America ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
First Century ◽  
Future Change ◽  
Twenty First Century

scholarly journals Evaluation of regional climate models ALARO-0 and REMO2015 at 0.22° resolution over the CORDEX Central Asia domain

2020 ◽  
Author(s):  
Sara Top ◽  
Lola Kotova ◽  
Lesley De Cruz ◽  
Svetlana Aniskevich ◽  
Leonid Bobylev ◽  
...  
Keyword(s):  
High Resolution ◽  
Central Asia ◽  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Horizontal Resolution ◽  
Maximum Temperature ◽  
Climate Projections ◽  
Climate Information ◽  
Climate Data

Abstract. To allow for climate impact studies on human and natural systems high-resolution climate information is needed. Over some parts of the world plenty of regional climate simulations have been carried out, while in other regions hardly any high-resolution climate information is available. This publication aims at addressing one of these regional gaps by presenting an evaluation study for two regional climate models (RCMs) (REMO and ALARO-0) at a horizontal resolution of 0.22° (25 km) over Central Asia. The output of the ERA-Interim driven RCMs is compared with different observational datasets over the 1980–2017 period. The choice of the observational dataset has an impact on the scores but in general one can conclude that both models reproduce reasonably well the spatial patterns for temperature and precipitation. The evaluation of minimum and maximum temperature demonstrates that both models underestimate the daily temperature range. More detailed studies of the annual cycle over subregions should be carried out to reveal whether this is due to an incorrect simulation in cloud cover, atmospheric circulation or heat and moisture fluxes. In general, the REMO model scores better for temperature whereas the ALARO-0 model prevails for precipitation. This publication demonstrates that the REMO and ALARO-0 RCMs can be used to perform climate projections over Central Asia and that the produced climate data can be applied in impact modelling.

Precipitation extremes over southern South America and their synoptic environment in a set of CORDEX regional climate models

2021 ◽  
Author(s):  
Matias Ezequiel Olmo ◽  
Maria Laura Bettolli
Keyword(s):  
South America ◽  
Extreme Precipitation ◽  
Climate Models ◽  
Regional Climate ◽  
Extreme Rainfall ◽  
Regional Climate Models ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Circulation Types ◽  
Observational Uncertainty

<p>Southern South America (SSA) is a wide populated region exposed to extreme rainfall events, which are recognised as some of the major threats in a warming climate. These events produce large impacts on socio-economic activities, energy demand and health systems. Hence, studying this phenomena requires high-quality and high-resolution observational data and model simulations. In this work, the main features of daily extreme precipitation and circulation types over SSA were evaluated using a 4-model set of CORDEX regional climate models (RCMs) driven by ERA-Interim during 1980-2010: RCA4 and WRF from CORDEX Phase 1 and RegCM4v7 and REMO2015 from the brand-new CORDEX-CORE simulations. Observational uncertainty was assessed by comparing model outputs with multiple observational datasets (rain gauges, CHIRPS, CPC and MSWEP). </p><p>The inter-comparison of extreme events, characterized in terms of their intensity, frequency and spatial coverage, varied across SSA exhibiting large differences among observational datasets and RCMs, pointing out the current observational uncertainty when evaluating precipitation extremes, particularly at a daily scale. The spread between observational datasets was smaller than for the RCMs. Most of the RCMs successfully captured the spatial pattern of extreme rainfall across SSA, reproducing the maximum intensities in southeastern South America (SESA) and central and southern Chile during the austral warm (October to March) and cold (April to September) seasons, respectively. However, they often presented overestimations over central and southern Chile, and more variable results in SESA. RegCM4 and WRF seemed to well represent the maximum precipitation amounts over SESA, while REMO showed strong overestimations and RCA4 had more difficulties in representing the spatial distribution of heavy rainfall intensities. Focusing over SESA, differences were detected in the timing and location of extremes (including the areal coverage) among both observational datasets and RCMs, which poses a particular challenge when performing impact studies in the region. Thus, stressing that the use of multiple datasets is of key importance when carrying out regional climate studies and model evaluations, particularly for extremes. </p><p>The synoptic environment was described by a classification of circulation types (CTs) using Self-Organizing Maps (SOM) considering geopotential height anomalies at 500 hPa (Z500). Specific CTs were identified as they significantly enhanced the occurrence of extreme rainfall events in sectorized areas of SESA. In particular, a dipolar structure of Z500 anomalies that produced a marked trough at the mid-level atmosphere, usually located east of the Andes, significantly favoured the occurrence of extreme precipitation events in the warm season. The RCMs were able to adequately reproduce the SOM frequencies, although simplifying the predominant CTs into a reduced number of configurations. They appropriately reproduced the observed extreme precipitation frequencies conditioned by the CTs and their atmospheric configurations, but exhibiting some limitations in the location and intensity of the resulting precipitation systems.</p><p>In this sense, continuous evaluations of observational datasets and model simulations become necessary for a better understanding of the physical mechanisms behind extreme precipitation over the region, as well as for its past and future changes in a climate change scenario.</p>

Sign in / Sign up

Export Citation Format

Share Document